Retractable shoe surface finishing machine



Nov. '4, 1941. B. F. FOWLER RETRACTABLE SHOE SURFACE FINISHING MACHINE Filed Dec. 29, 1938 2 Sheets-Sheet l INVENT OR. P7 F FOWAE'E Nov. 4, 1941. B. F. FOWLER RETRACTABLE SHOE SURFACE FINISHING MACHINE 2 Sheets-Sheet 2 File (1 Dec. 29, 1958 Patented Nov. 4, 1941 RETRACTABLE SHOE sUREACE FINISHING MACHINE V Bert F. Fowler, south Bend, 1nd. A

Application December 29, 1938, Serial No. 248,279

7 Claims.

This invention relates to surface finishing and more particularly to an improved apparatus for finishing metallicrsurfaces by a moving abrasive belt or the like.

In my co-pending United States patent applications Serial No. 139,406, filedApril 28, 1937, and Serial No. 190,254, filed February 12,1938, I have described and claimed metal finishing machines embodying certain novel features and im-,

provements. The present invention is particularly adapted for use with machines of the type described in said co-pending applications, but is, of course, not limited to use only with such machines.

In my co-pending applications I have disclosed sanding machines which consist essentially of spaced belt supporting pulleys, one of. which is driven, a driving belt encompassing said pulleys, an abrasive belt supported by the driving belt and driven thereby, and a belt supporting shoe member disposed between the supporting pulleys in a position to back up the belts. v

In the metal finishing operations which are necessary in automobile body work and the like, fiat,.- convex and concave surfaces are ,encountered. In finishing fiat or concave surfaces it is desirable to have the abrasive belt supportedby a backing shoe member on one of the reaches between the driving. and supporting pulleys.

one without a shoe, or to stop the finishing operations and go through the usually rather involved. process of removing the shoe from the machine when it is desired to work on a convex surface. This latter procedure is impractical in production shops. a

It is among the objects of the present invention to provide a surface finishing machine of the type described which is practically instantane ously adaptable to finishing fiat, concave or convex surfaces. Other objects of my invention are the provision of an improved surface finishing machinehaving a backing shoe which may be moved into or out of backing position by the operator without removing his hands from operating position on the handles of the machine; the provision of a resiliently supported backing be effectively finished; the provision of a reshoe which may be moved into and out of backing position and which, whenout of backing position, will permit the sanding belt to be curved inwardly and assume a concave formbetween the spaced supporting rollers whereby convex surfaces may tractable shoe in a surface finishing machine; the provision of a resilient, retractable air cush-v ion type shoe having simple and compact operating mechanism whereby it may instantaneously be moved into either operating or retracted posi .tion.

The above and other objects of my invention will appear from the following description of one embodiment thereof, reference beinghad to the accompanying drawings, in'which- V Figure 1 is a side elevation of a surface finishing machine embodying my improved retractable shoe.

Figure 2 is a view taken substantially on line 2-2 of Figure 1 and illustrating the control connections for the shoeoperating mechanism.

Figure 3 is an enlarged detached side elevation of my retractable shoe mechanism, the shoe being shown in belt engaging or operating position.

Figure 4 is a view generally similar to Figure 3 but illustrating the shoe inretracted position,

for use on convex work., v v

Figure 5 is an enlargedfragmentary view taken on line 55 of Figure 3.- Y

Figure 6 isa detachedfragmentary viewshow- I ing the control valve andfluid conducting .con-

nections thereto, the valve being in' p osition to permit the shoe to be in operatingposition as seen in Figure 3 and air to be supplied to form the belt cushion thereon. 1

Figure 7 is a view similar to Figure 6 but,il1ustrating the position of the control valvewhen the shoe is in retracted position as seen in Figure 4, and the cushioningair supply to the shoeis shut off. i

In the drawings the frame of the surface finishingmachine is indicated at I. This frame carries belt supporting pulleys 2 and 3, the pulley 3 being driven andthe pulley 2 being an idler pulley which is preferably mountedon a pivotal support and adapted'to be move d toward and away from the drivingpulley 3 by means of the hand lever 4, as is fully described in my copending U. S. application, Serial No. 190,254, filed February 12, 1938.

The frame I also carries pivoted arms 5 and 6 which in turn rotatably support the auxiliary rollers 1 and 8. Springs 9 and I 0 extend from the arms 5 and 6, to. the main frame of the machine and tend to exert a force on the arms to move the rollers l and 8 towards each other and to maintain the driving belt ll out of its normal straight line path between the pulleys 2 and 3. The surface finishing belt l2, commonly of abrasive material, overlies the driving belt H and an idler pulley 13 may be provided to maintain the driving belt I I out of contact with the finishing belt l2 along one reach between pulleys 2 and 3. The belt supporting shoe M, as is most clearly seen in Figures 3, 4 and 5, preferably has a grooved belt engaging surface I and is pro-' vided with four inwardly projecting supporting; rods l6. Cushioning air is supplied to the grooves,

of the surface 15 through a flexible hose l1 con,- nected to a transversely extending header 18 which opens into each of the .grooves'in' the sur"- face 15 and which is disposed at the end of the shoe first engaged by the on-coming belt. This air cushioning type. of shoe is also fully described and claimed in 4 my co-pending U. S. application Serial No.190,254, filed February 12, 1938.

A leaf spring l9; having its ends preferably curledinwardly at-lfl and.2 l, is fixedat its center by a screw.22.to thebracket 23 whichin turn is secured totheframe I of the machine. The supporting rods lit for the shoe [4 pass through slotted apertures24 in the spring l9 and extend down through and have free sliding fits in holes inthe transverse bar members Hand 26. Heads 16 are formed on the ends of screws I6. In-

Wardly projecting central flanges or lugs 2'1 and 28.nare provided on the bars 25 and 2fi and have pivotal connectionwith links 29 and 30', The opposite ends of thelinks-29and :33 are in turn pivotally connected at .3 I. and 32:respectively, to the-operating levers 33 and and the inner ends, of the levers 33 and 34 are pivotally conected-to the flxed bracket 23 at 35 and 36.

Aconnecting yokel3'l is pivotally secured at its ends. to links 38, and 39 which "are in turn pivotally securedat their opposite ends to the operating levers 34 and 33rrespectively. One end of the main retracting lever 40 is pivotally attached at 4 I. to the center of the yoke 31. and the lever 40 .in turn pivotallymounted on the-main frame I by a suitable stud'42 or the like..

The retracting mechanism power source comprises an air cylinder 43 having. a-movable member, such as a piston, therein and anroperating rod or. plunger 44 projecting: therefrom.v The rod 44. is positionedto engage theend 40'of the lever 40-which is oppositeto andon the other side of the pivotal center 42 from theconnection to the yoke 31.

Before explaining the'control mechanism; for controlling the fluid pressure connectionsto effect operatingrmovement of the piston in 'the cylinder 43 it willbe in. order todescribethe action of the shoe retracting mechanism.

In Figure 3 the shoe is shown-in working. or belt .supportingposition with the.outer surfacethereof engaging the, inner.- surfaceof the driving belt H.v The endse20-and 21 .of the leaf spring t9. bear againsttheinner surface of the shoe 1 4,. adjacent its-ends,- andexert a force tending to. push. the. shoe l4. outwardly into supporting engagement with, the belt H.. This outward movement may belimitedby the heads [6. The

shoe is floatingly mounted upon the spring [3 and. is restrained. from. laterahmovement, due to the action ofthe. belt upon the surface of the shoe, by means ofithe supporting rods or pins I6. However, substantially universal tilting or rocking movement of the shoe I4 is permitted because of the free fit of the supporting rods [6 in the slots 24 in the spring l9 and in the holes in the bars 25 and 26. Pressure of the belt 12 against the work will be transmitted to the shoe l4 and opposed by the spring IS.

The spring l9 normally continuously exerts a force tending to move the shoe 14 toward the belts and away from the center line of the pulleys 2 and 3. Although I have illustrated a leaf spring arrangement, it will be understood by those skilled in the art that other types of spring or flexible or resilient supporting means may be employed for the shoe [4 without departing from the spirit of my invention.

When it is desired to operate the sanding machine with the shoe out of engagement with the belt; as for example when it is desired to finish a convex surface, fluid pressure is applied to the cylinder 43, in a manner to be later more fully described; and the piston rod or plunger 44 moved outwardly pushing against the. end, 40 of the lever 40. The movement of the lever 48 will cause the yoke 31 to be drawn inwardly or in a directionaway from the shoe M, This movement will be transmitted to. the operating levers 33 and 34 through the links 38. and 39 andrfrom the operating levers 33,and .34 to the transverse bars 25- and. 26 through the links 29 and 30. The inward movement ofthe bars, 25. and 26 will cause them to engage the enlarged heads l6 of the supporting rod 16 and pull inwardly thereon thuscompressing and flatteningthe leaf spring l9 and moving the shoe [4 entirely out of contact with the belt H into the position shown in Figure: 4. The ends 20 and 2| .of the spring IE] will, of. course, move apart during, this flattening of. the spring i9 andwillmerely slideover the inner surface of the shoe 14. As long. as. sufficient, air pressure is maintained inthe cylinder 43...to overcome the spring l9 the shoe. l4 will be retained in its retracted position. However, as soon as. the air pressure. in the cylinder 43 is released the spring l9 will snap the. shoe supporting parts ,back into the position shown in Figure 3 and return the shoe to supportingposition relative to the belt. As is seen in Figure 4, suflicient clearance is established between the shoe l4 and the belt II to permit the belts to assume a substantially concave contour between. the supporting rollers 1 and 8 and it will be evident that the. flexibility and adaptability of a. surface finishing machine. is greatly increasedby means of my instantaneously operable shoe. retracting mechanism.

In order that the operator may. at all times control the position of the shoe and move it into or out of belt engaging position While operating the machine I provide a control valve V which is mountedon the handle 45. On the opposite handle 46 aswitch 41 may be mounted for controlling the operation of the motor which. drives the pulley.3 and the belts H and I2.

The pipe or tube I'I extends from the shoe l4 to the valve V. Another pipe or tube 48 extends from the valve V to the cylinder 43 and a third pipe or tube 49 connects the valve V to any suitabletsource of supply of fluid pressure, preferably compressed air.

Referring particularly to Figures 6 and 7, the valve V includes a plunger 50 disposed in atubular sleeve 5! and having an operating head or handle 52 disposed for convenient manipulation by the workman. When the valve plunger 50 is in its inner position, as shown in Figure 6, the air supply pipe 49 is connected through the annular grooves 53 to the pipe I! which leads to the grooves in the face of the shoe [4. At the same time the grooved or cut out portion 54 of the plunger 50 connects the pipe 48 leading from the air cylinder 43 to the atmosphere through an opening 55 in the housing of the valve V. The shoe, plunger 44 and the operating linkage will now be in the position shown in Figure 3 with the shoe backing up and supporting the belts II and I2.

When the operator releases his finger from the head 52 the spring 56 will move the plunger 50 into the position shown in Figure '7. Now the pipe I! which leads to the grooves in the shoe surface will be shut off from the supply line 49 and the pipe 48 which leads to the operating cylinder 43 will be connected to the supply line 49 by the groove or slot 54. .The atmospheric connection 55 will be shut off from the cylinder 43 by the end of the plunger 55, When the air pressure from the supply line 49 is applied to the cylinder 43 the plunger 44 will be pushed outwardly engaging the lever 40 and retracting the shoe, as explained above, into the position shown in Figure 4. At the same time the valve V shuts off the supply of air to the face of the shoe l4 and thus prevents wasteful discharge of air into the slots in the shoe when unnecessary.

As long as the operator holds the plunger 55 in the position shown in Figure 6 the shoe will be in belt engaging position. As soon as he removes pressure from the head 52 of the plunger 50 the valve will shift to cause retraction of the shoe and shut off the air supply to the shoe.

bodiment of my invention in considerable detail' it will be understood by those skilled in the art that numerous variations and modifications may be made in the apparatus employed to operate my retractable shoe and I do not, therefore, wish to be limited to the specific constructions and linkages herein illustrated alnd described, but claim as my invention all embodiments thereof coming within the scope of the appended claims.

I claim:

1. In a surface finishing machine, a frame, spaced belt supporting rolls carried by said frame, a belt engaging said rolls, a belt backing shoe adapted to engage said belt between saidrolls, resilient supporting means for said shoe, said supporting means being mounted on said frame and exerting a pressure against said shoe tending to cause engagement between said belt and shoe, and fluid pressure actuated means for moving said shoe out of engagement with said belt against the pressure exerted by said resilient supporting means.

2. In a surface finishing machine, a frame, spaced belt supporting rolls carried by said frame, a belt engaging said rolls, a belt backing shoe adapted to engage said belt between said rolls, resilient supporting means for said shoe, said supporting means being mounted on said frame and exerting a pressure against said shoe tending The operator may thus retract the shoe whenever the to cause engagement between said belt and shoe, fluid pressure actuated means for moving said shoe out of engagement with said belt against the pressure exerted by said resilient support means, and valve means for controlling the operation of said fluid pressure actuated means whereby said shoe maybe retracted from or released into belt engaging position.

3. In surface finishing apparatus, a flexible belt, means for supporting and driving said belt, a backing shoe positioned to engage and resiliently support said belt, means for discharging fluid under pressure between said belt and said shoe, fluid pressure actuated means for retracting said shoe from belt engaging position, and valve means adapted. when in one position to connect a source of fluid under pressure to said means for discharging fluid between said belt and shoe and shut off the fluid under pressur from said fluid pressure actuated retracting means and when in another position to connect the supply to the retracting means and shut off the supply from the means for discharging fluid between said belt and shoe.

4. In apparatus of the type described a frame,

spaced pulleys carried by said frame, a belt supported by said pulleys, a shoe adapted to engage said belt between said pulleys, a spring mounted on said frame and; engaging said shoe whereby said shoe will be resiliently urged into engagement with said belt, means for restraining said shoe from substantial movement in the direction of belt travel while permitting movement of said shoe towards or away fromsaid belt, a lever fulcrumed on said frame, operating linkag between said lever and said shoe, fluid pressure actuated means for moving said lever in a direction to retract said shoe out of engagement with said belt, said spring being adapted to move said shoe in the opposite direction, and valve means for controlling said fluid pressure actuated means.

5. In apparatus of the type described, a frame, spaced pulleys carried by said frame, a belt supported by said pulleys, a shoe adapted to engage said belt between said pulleys, a spring mounted on said frame and engaging said shoe whereby said shoe will be resiliently urged into engagement with said belt, means for restraining said shoe from substantial movement in th direction of belt movement while permitting movement of said shoe towards or away from said belt, a lever fulcrumed on said frame, operating linkage between said lever and said shoe, fluid pressure actuated means for moving said lever in a direction to retract said shoe out of engagement with said belt, said spring being adapted to move said shoe in th opposite direction, said shoe having a grooved belt engaging surface, fluid pressure conducting connections for conveying fluid to said grooved surface, and valve means for controlling the flow of fluid under pressure to said shoe and to said pressure actuated means.

6. In a portable sanding machine having a supporting and operating handle and a moving belt, a retractable shoe adapted in one position to back up and support said belt and in another position to be entirely removed from engagement with said belt, means for substantially instantaneously moving said shoe into and out of its retracted position, and means, mounted on said handle of the machine within reach of the hand of the operator without releasing the grasp of said hand on said handle, for controlling said shoe moving means.

7. In a surface finishing machine, a frame, a

supporting and operating handle onsaid frame, spaced belt supporting rolls carried by said frame, a belt engaging said rolls, a belt backing shoe adapted to engage said belt between said rolls, resilient supporting means for said shoe, said supporting means being mounted on said frame and exerting a pressure against said shoe tending to cause engagement between said belt and shoe,

fluid pressure actuated means for moving said shoe out of engagement with said belt against the pressure exerted by said resilient supporting means, and means, mounted on said handle of the machine Within reach of the hand of the operator while grasping said handle, for controlling said fluid pressure actuated means.

BERT F. FOWLER. 

